1. Field of Invention
The present invention relates to an optical waveguide manufacturing process and, in particular, to a manufacturing process for preparing sol-gel optical waveguides.
2. Related Art
Among various opto-electronic devices using plane optical waveguide technology, silica has been used in semiconductor processes due to its superior resistance to environments and optical properties for many decades. Conventionally the manufacturing of silica plane waveguide materials is achieved mainly by using flame hydrolysis deposition (FHD), ion exchange, chemical vapor deposition (CVD), and sol-gel.
FHD and CVD involve expensive semiconductor equipment and have a higher cost. The advantage of using sol-gel is in that it can be prepared by employing only the spinning or dipping method. Therefore, its cost is much cheaper than other plane optical waveguide processes.
With regard to single/multiple mode plane optical waveguide manufacturing, many researches and papers had been published by, for instance, Ecole Polytechnique in Canada, QPS, Universite de Montpellier II in France, Physical Optical Cooperation in the U.S. recently. In particular, preparing plane optical waveguides using photosensitive sol-gel has a lower cost than adopting conventional high temperature processes. It has such advantages as UV imprinting/curing, an adjustable refractivity, etc, which are particularly preferable for preparing optical waveguides.
Since the single mode plane optical waveguide requires a core layer with a thickness of 6 to 8 xcexcm and the multiple mode plane optical waveguide requires a core layer with a thickness larger than 50 xcexcm, the silicon substrate employed must have a buffer layer with a thickness greater than 10 xcexcm. Using the FHD and CVD methods demands expensive semiconductor equipment with special specifications and would increase the cost. Therefore, adopting the sol-gel manufacturing processes is a practical and cost-effective choice.
However, according to the technical contents disclosed in the U.S. Pat. No. 5,130,397, entitled xe2x80x9cHybrid Sol-Gel Optical Materialsxe2x80x9d, only thin films with a thickness smaller than 10 xcexcm can be prepared at a time. It is noted that currently researches have been focused on single mode optical waveguides prepared by using photosensitive sol-gel. But little knowledge is known in producing multiple mode plane optical waveguides with a core layer of thickness greater than 50 xcexcm and silicon substrates with a buffer layer of thickness greater than 10 xcexcm.
It is thus a primary object of the present invention to provide a manufacturing process for preparing sol-gel optical waveguides that simultaneously solves the problems existing in the prior that only thin films with a thickness smaller than 10 xcexcm can be made at a time and cracking phenomena associated therewith, that no multiple mode plane optical waveguide can be manufactured to have a core layer with a thickness greater than 50 xcexcm, and that no silicon substrate can be prepared to have a buffer layer with a thickness greater than 10 xcexcm.
The sol-gel optical waveguide manufacturing process of the present invention comprises the steps of: preparing sol-gel ingredients, manufacturing optical waveguide photoresist modules, spinning sol-gel, baking optical waveguide modules, and forming a sol-gel plane optical waveguide.